Saw with a tool guidance mechanism with guide elements adjustable to the tool size

ABSTRACT

The invention is based on a saw, in particular a hand-guided saber saw, which has a drive unit ( 10 ) by way of which a tool ( 12 ), in particular a saw blade, can be driven, and with a tool guide mechanism ( 14 ), by way of which the tool ( 12 ) can be guided laterally by guide elements ( 16, 18 ). It is proposed that the tool guide mechanism ( 18 ) has a control motor ( 20 ), by way of which a spacing between the guide elements ( 16, 18 ) can be adjusted to a tool thickness.

PRIOR ART

[0001] The invention is based on a saw with a tool guide mechanism, asgenerically defined by the preamble to claim 1.

[0002] From German Utility Model DE 299 10 173 U1, a saw of this generictype is known, specifically a hand-guided saber saw. The saber saw has adrive unit, to which a saw table is secured. Via the drive unit, a sawblade can be driven periodically with an up-and-down motion. The sawblade is secured by one end in the drive unit and beginning at the driveunit extends downward, perpendicular to a working direction, through thesaw table and with its free end protrudes past the saw table.

[0003] To prevent the saw blade from deflecting laterally in response tothe transverse forces that occur in the sawing process, as can occurespecially when cutting radii, a tool guide mechanism is provided. Thetool guide mechanism has two support arms, disposed laterally of the sawblade, on which arms so-called stabilizing elements or guide elementsare secured, which rest laterally on the saw blade and guide itlaterally. The support arms are joined together via an adjusting screw,so that a spacing between the guide elements can be adjusted manually bya user to a saw blade thickness. A securing bracket is also secured tothe support arms; it precedes the saw blade in the machining directionand forms a touch guard.

ADVANTAGES OF THE INVENTION

[0004] The invention is based on a saw, in particular a hand-guidedsaber saw, which has a drive unit by way of which a tool, in particulara saw blade, can be driven, and with a tool guide mechanism, by way ofwhich the tool can be guided laterally by guide elements.

[0005] It is proposed that the tool guide mechanism has a control motor,by way of which a spacing between the guide elements can be adjusted toa tool thickness. The ease of use can be enhanced, especially if thetool guide mechanism is adjusted automatically via the control motor, assoon as a new tool is secured in the saw. However, the control motorcould certainly be activated by a manual actuation, for instance of aswitch. Moreover, with automatic adjustment, an advantageous guideadjustment and an attendant optimal outcome of sawing are alwaysassured. An incorrect adjustment is avoidable.

[0006] The control motor can have an electrical, electromagnetic,pneumatic, hydraulic, chemical and/or biochemical drive mechanism, witha linearly and/or rotationally moved power takeoff, and so forth.Especially advantageously, however, the control motor has a spring drivemechanism, and as a result it can be embodied especially simply in termsof construction as well as especially economically and sturdily.

[0007] An undesired opening of the tool guide mechanism can be achievedby means of various nonpositive- and/or positive-engagement mechanismsthat appear useful to one skilled in the art, such as a detent mechanismthat snaps into place as soon as a desired position is reached; thedesired position can in turn be detected by various sensors, such asoptical, mechanical and/or electrical sensors, and so forth.

[0008] Fundamentally, it is also conceivable to make the closing forcesof the control motor greater than the transverse forces typicallyoccurring during operation.

[0009] However, if after an adjustment operation, the tool guidemechanism is kept in its closing position by a nonpositive-engagementclamping mechanism based on self-locking, an infinitely variableadjustment can be attained in a structurally simple and economical waywith only a few components and little additional weight, and anundesired opening of the tool guide mechanism can be securely avoided.Especially in a control motor with a spring drive mechanism, the springelements can be embodied as small, lightweight and economically, andhigh friction can be avoided as a consequence of a high continuouscontact pressure of the guide elements of the tool guide mechanismagainst the tool.

[0010] The self-locking can be achieved by a thread, for instance of anadjusting screw driven by an electric motor, or by some other componentcorresponding with an oblique face, and so forth.

[0011] In a further feature of the invention, it is proposed that thetool guide mechanism has pivot arms, connected via a joint, on whicharms guide elements are disposed, as a result of which, a symmetricalpositioning of the guide elements from two sides against the tool can beachieved in a structurally simple and space-saving way with a controlmotor. If the pivot arms are drivable in their pivoting motion viaoblique faces, then a desired self-locking in the opening position ofthe tool guide mechanism can be realized in a simple way.

[0012] It is also proposed that the oblique faces are formed by adisplaceably supported bearing component, which forms a part of thecontrol motor and is urged in the direction of its closing position viaat least one spring element, and that for opening the tool guidemechanism, a control device is displaceable out of its closing positioninto an opening position via a control element. The self-locking can beundone easily by a user, and a structurally simple tool guide mechanismwith only a few additional components can be achieved.

[0013] If the guide elements are disposed on a first side of the jointof the pivot arms, and the control motor is disposed on a second side ofthe joint, the installation space can advantageously be utilized, andthe control motor can be disposed in concealed fashion in a housing ofthe saw and thereby protected from external factors. Moreover, thisprevents the control motor from impairing the view of the tool and theworkpiece.

[0014] If the pivot arms of the tool guide mechanism precede the tool inthe machining direction, then these arms can advantageously form a guarddevice or a touch guard. Additional components, weight, assembly effortand expense for a corresponding guard device can be avoided.

[0015] The operation of adjusting the tool guide mechanism takes placeas a rule after a tool change. If a control device for opening the toolguide mechanism is coupled at least operatively with a control device ofa fastening mechanism of the tool, specifically in such a way that uponopening of the fastening mechanism the tool guide mechanism issimultaneously opened, then actuation operations that a user mustperform can be avoided, and the ease of use can be enhanced stillfurther. Moreover, additional components can be dispensed with if thecontrol device for opening the tool guide mechanism is embodied at leastpartly integrally with the control device of the fastening mechanism ofthe tool.

[0016] In a further feature of the invention, it is proposed that thetool guide mechanism can be kept in an opening position via a retainingdevice after the removal of the tool. An automatic positioning beforethe insertion of a new tool, and thus a requisite opening for insertinga new tool, can advantageously be avoided. After the new tool has beenintroduced, the retaining mechanism can be released either manually oradvantageously automatically by the introduction of the tool.

[0017] If the guide elements of the tool guide mechanism are formed byroller bodies, then especially slight friction, a low power loss, andlittle wear can be achieved. To avoid high pressure per unit of surfacearea between the guide elements and the tool, the roller bodies can beadapted to the contour of the tool, or can be made adaptable. The rollerbodies can be formed by concave, convex or cylindrical rollers or byballs and so forth. Instead of roller bodies, the guide elements of thetool guide mechanism can advantageously be formed of ceramic parts,which can be made especially wear-resistant. In addition, retainingelements can simply be formed onto ceramic parts, examples being detentelements or a thread and so forth. In principle, however, guide elementsmade of other materials that appear useful to one skilled in the art,such as hard metal, and so forth, are also conceivable.

[0018] If the guide elements are held by detachable retaining elementsand are replaceable, then with economical guide elements a long servicelife of the tool guide mechanism can be attained. Moreover, guideelements with good lubricating properties, which besides a guidefunction lubricate the tool, can be used, such as carbon-based guideelements, and so forth.

[0019] The embodiment of the invention can be employed in variousstationary and hand-guided saws that appear appropriate to one skilledin the art, such as band saws and so forth. Especially advantageously,however, the embodiment of the invention is employed in hand-guidedsaber saws. In hand-guided saber saws, a tool change is a rule donefrequently, so that in such saws, an especially major enhancement to theease of use can be attained with the embodiment of the invention.

DRAWING

[0020] Further advantages will become apparent from the ensuingdescription of the drawing. In the drawings, one exemplary embodiment ofthe invention is shown. The drawings, description and claims includenumerous characteristics in combination. One skilled in the art willexpediently consider the characteristics individually as well and putthem together to make useful further combinations.

[0021] Shown are:

[0022]FIG. 1, a saber saw shown schematically obliquely from above;

[0023]FIG. 2, a detail II of FIG. 1, shown enlarged and including a toolguide mechanism;

[0024]FIG. 3, the detail II obliquely from the front;

[0025]FIG. 4, the detail II directly from the front;

[0026]FIG. 5, the detail II obliquely from the front without the cover;

[0027]FIG. 6, the tool guide mechanism of FIG. 2 from behind; and

[0028]FIG. 7, a single pivot arm of the tool guide mechanism of FIG. 2,in the dismantled state.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

[0029]FIG. 1 schematically shows a hand-guided saber saw obliquely fromabove; it has an electric motor 10, not shown in further detail,disposed in a housing 50. In the saber saw, a saw blade 12 is secured,which is firmly joined by its first end in the housing 50 to a gear unitdriven by the electric motor 10 and extends downward, beginning at thefirst end, perpendicular to the machining direction 44, through a sawtable 52 shown only in suggested fashion in FIG. 1. With the electricmotor 10, via the gear unit, the saw blade 12 can be driven periodicallyup and down in a reciprocating motion, essentially perpendicular to amachining direction 44. On a side remote from a working side of the sawblade 12, the saw blade 12 is braced against a support roller 70, by wayof which the saw blade 12 can be driven, swinging in the machiningdirection 44.

[0030] The saber saw also has a tool guide mechanism 14, by way of whichthe saw blade 12 can be guided laterally with guide elements 16, 18(FIGS. 1 and 4). According to the invention, the tool guide mechanism 14has a control motor with a spring drive mechanism, by way of which aspacing between the guide elements 16, 18 is adjustable to a saw bladethickness. The tool guide mechanism 14 has two pivot arms 26, 28, joinedvia a joint 24, to which arms the guide elements 16, 18, formed ofceramic parts, are secured on one end via retaining elements 46, 48(FIGS. 2-7). The pivot arms 26, 28 form a kind of guide tongs. The guideelements 16, 18 are glued to the retaining elements 46, 48, which aresecured releasably and replaceably to the pivot arms 26, 28 viafastening screws 54, 56.

[0031] Guide bolts 58, 60 (FIG. 6 and FIG. 7) are formed onto a secondend of the pivot arms 26, 28. The guide bolts 58, 60 protrude in theactuation direction 44 into grooves 62, 64 of a bearing component 34,which grooves are embodied such that they diverge slightly obliquely, inthe longitudinal direction of the saw blade 12, relative to the housing50, at an angle of less than 6°. By oblique faces 30, 32 of the bearingcomponent 34 in the grooves 62, 64, the pivot arms 26, 28 can be drivenin their pivoting motion. The bearing component 34 is supporteddisplaceably parallel to the longitudinal direction of the saw blade 12and forms one part of the control motor 20, specifically because thebearing component 34 is urged in the direction of its closing position,that is, in the longitudinal direction of the saw blade 12 relative tothe housing 50, via two helical compression springs 40, 42. The helicalcompression springs 40, 42 are each braced by an end remote from thebearing component 34 on contact faces, not identified by referencenumeral, formed on a cover 66. The control motor 20, formed by thebearing component 34 and the helical compression springs 40, 42, isconcealed behind the cover 66 on the side of the joint 24 remote fromthe guide elements 16, 18 and thus protected against external factors.

[0032] For changing the saw blade 12, a displaceably supported controlelement 36 of a control device 38 of the tool guide mechanism 14 isdisplaced crosswise to the machining direction 44, along an oblique face68 formed onto the bearing component 34, as a result of which thebearing component 34 is displaced out of its closing position into itsopening position, in the longitudinal direction, remote from the housing50, of the saw blade 12. The guide bolts 58, 60 are guided and pivotedapart along the oblique faces 30, 32, as a result of which the guideelements 16, 18, disposed on the opposite side of the joint 24, arelikewise pivoted apart and lift away from the saw blade 12.

[0033] The control element 36 of the control device 38 of the tool guidemechanism 14 is embodied integrally with a control element of afastening mechanism, not identified by reference numeral, of the sawblade 12; specifically, by the displacement of the control element 36 inthe direction of the oblique face 68 of the bearing component 34, thefastening mechanism of the saw blade 12 is released, and the saw blade12 is ejected.

[0034] As long as a new saw blade 12 is not introduced into the sabersaw and secured via the fastening mechanism, the tool guide mechanism 14and the bearing component 34 are held in their opening position by adetent mechanism, not identified by reference numeral, so that by meansof the guide elements 16, 18, a new saw blade 12 can simply beintroduced into the saber saw or into the fastening mechanism. Withoutsuch a detent mechanism, the bearing component 34, for introducing a newsaw blade 12, would have to be displaced into its opening position, forinstance by means of the control element 36. The control element 36 isreturned via a restoring spring, not identified by reference numeral.

[0035] When the new saw blade 12 is introduced, simultaneously with thefastening of the saw blade 12 by the fastening mechanism, the detentmechanism is released, and the bearing component 34 is displaced in itsclosing position by the helical compression springs 40, 42. The guidebolts 58, 60 are guided in the grooves 62, 64 along the oblique faces30, 32 and are pivoted toward one another, as a result of which theguide elements 16, 18 are likewise pivoted toward one another and restlaterally on the saw blade 12. The tool guide mechanism 14 adjustsautomatically to a thickness of a given saw blade 12 employed, and aspacing between the guide elements 16, 18 is adjustable to saw bladeswith a thickness between 0.8 and 1.7 mm.

[0036] The guide bolts 58, 60 and the oblique faces 30, 32 of thebearing component 34 form a clamping mechanism 22, by which the pivotarms 26, 28 of the tool guide mechanism 18, after the adjustmentoperation, are kept in the closing position by self-locking. ReferenceNumerals 10 Drive unit 12 Tool 14 Tool guide mechanism 16 Guide element18 Guide element 20 Control motor 22 Clamping mechanism 24 Joint 26Pivot arm 28 Pivot arm 30 Oblique face 32 Oblique face 34 Bearingcomponent 36 Control element 38 Control device 40 Spring element 42Spring element 44 Machining direction 46 Retaining element 48 Retainingelement 50 Housing 52 Saw table 54 Fastening screw 56 Fastening screw 58Guide bolt 60 Guide bolt 62 Groove 64 Groove 66 Cover 68 Oblique face 70Support roller

1. A saw, in particular a hand-guided saber saw, which has a drive unit(10) by way of which a tool (12), in particular a saw blade, can bedriven, and with a tool guide mechanism (14), by way of which the tool(12) can be guided laterally by guide elements (16, 18), characterizedin that the tool guide mechanism (18) has a control motor (20), by wayof which a spacing between the guide elements (16, 18) can be adjustedto a tool thickness.
 2. The saw of claim 1, characterized in that thecontrol motor (20) has a spring drive mechanism.
 3. The saw of claim 1or 2, characterized in that after an adjustment operation, the toolguide mechanism (14) is kept in its closing position by anonpositive-engagement clamping mechanism (22) based on self-locking. 4.The saw of one of the foregoing claims, characterized in that the toolguide mechanism (14) has pivot arms (26, 28), connected via a joint(24), on which arms the guide elements (16, 18) are disposed.
 5. The sawof claim 4, characterized in that the pivot arms (26, 28) are drivablein their pivoting motion via oblique faces (30, 32).
 6. The saw of claim5, characterized in that the oblique faces (30, 32) are formed by adisplaceably supported bearing component (34), which forms a part of thecontrol motor (20) and is urged in the direction of its closing positionvia at least one spring element (40, 42), and that for opening the toolguide mechanism (14), a control device (38) is displaceable out of itsclosing position into an opening position via a control element (36). 7.The saw of one of claims 4-6, characterized in that the guide elements(16, 18) are disposed on a first side of the joint (24) of the pivotarms (26, 28), and the control motor (20) is disposed on a second sideof the joint (24).
 8. The saw of one of claims 4-7, characterized inthat the pivot arms (26, 28) of the tool guide mechanism (14) precedethe tool (12) in the machining direction (44) and form a guard device.9. The saw of one of the foregoing claims, characterized in that acontrol device (38) for opening the tool guide mechanism (14) is coupledat least operatively with a control device of a fastening mechanism ofthe tool (12).
 10. The saw of claim 9, characterized in that the controldevice (38) for opening the tool guide mechanism (14) is embodied atleast partly integrally with the control device of the fasteningmechanism of the tool (12).
 11. The saw of one of the foregoing claims,characterized in that the tool guide mechanism (14) can be kept in anopening position via a retaining device after the removal of a tool(12).
 12. The saw of one of the foregoing claims, characterized in thatthe guide elements of the tool guide mechanism are formed by rollerbodies.
 13. The saw of one of claims 1-11, characterized in that theguide elements (16, 18) of the tool guide mechanism (14) are formed ofceramic parts.
 14. The saw of one of the foregoing claims, characterizedin that the guide elements (16, 18) are held by detachable retainingelements (46, 48) and are replaceable.